Improvement in telephones



A. K. EATON. Telephone.

Patented Dec. 9, 1879.

H 233% A 7. Q AWQ Win/asses UNITED STATES PATENT OFFICE.

ASAHEL K. EATON, OF BROOKLYN, NINV YORK.

IMPROVEMENT lN TELEPHONES.

Specification forming part of Letters Patent No. 222,475, dated December9, 1879; application filed May 16, 1878.

To all whom it may concern:

Be it known that I, AsAI-IEL K. EATON, of the city of Brooklyn, countyof Kings, and State of New York, have invented certain new and usefulImprovements in Telephonic Apparatus, of which the following is aspecifica tion.

My invention consists of the application of a multipolar magnet,consisting of a central compound bar, around which are uniformlydistributed a number of smaller bars, which are branches of the formerand of an opposite polarity to the diaphragm-plate of the tele phonictransmitter and receiver, for the purpose of increasing and distributingthe magnetic action upon and over the plate; and my invention consists,also, of the application of a series of slender sheet-steel U-shapedmagnets to the diaphragm of the receiving-telephone, to act inconjunction with the outer poles of the multipolar magnet, for the purpose of obtaining greater sensitiveness in the plate.

I make use of a multipolar magnet, consist ing of a central bar orcompound bar, around which are uniformly distributed a number of smallerbars which are branches of the former, and of an opposite polarity. Thecentral bar bein g a north pole at its upper extremity, the free ends ofthe smaller ones will all be south poles when magnetized. Upon thedifferent poles of this magnet induction-coils are fixed proportioned tothe magnetic power of the several poles.

In the drawings, Figure 1 represents the magnet in plan, with theinduction-coils I i i i '5 c iattached; and Fi 1, an elevation of thenaked magnet. The main central pole is marked and the siX small polesthat balance it, &c.'

The object in making use of this form ot magnet is not only to securemore powerful magnetic action upon the plate, but, more esk peciaily, todistribute that action over a considerable portion of the plate, insteadof confining it to the center, as hitherto. It enables me to make use ofplates of much larger diameter, thereby gaining in loudness without lossin distinctness of articulation.

The number of smaller poles used to bal anee the larger may be greateror less than represented, it being only requisite that, whatever thenumber, the smaller poles be arranged symmetrically around the larger.The number, however, should vary with the diameter of the plateemployed. With a diaphragm of six inches diameter I prefer a group oftwelve outer poles balancing a corresponding central one. The distanceof the outer poles from the central one will also vary with the size ofthe plate.

I increase the elasticity of the telephoneplate, without increasing itsthickness, by means o't'one or more corrugations. The larger the platethe greater the number required. It may be used singly, but, preferably,combined with one or more additional plates that may be either plain orcorrugated.

When a combination of plates is used they are separated at the edge by aring ofcard-board or otherwise, so as to inclose afilm of air, and theedges of the plates are cemented, so as to prevent its escape. The thinlayer of confined air acts as a cushion, preventin absolute contact, andserves to transmit vibrations from one plate to the other.

Fig. 2 is a plan of the single plate with its corrugations; Fig. 2, asection of the same, and Fig. 2" a section of the compound chamberedplate.

In the receiving-telephone I make use of a diaphragm of any sufficientlyelastic, non-magnetic,'or diamagnetic material, such as hard rubber,wood, card-board, sheet-brass, &c., to which are cemented a number. ofslender sheetsteel U-shaped magnets, corresponding to the number of theouter poles of the multipolar magnet. These are fixed symmetrically uponthe diaphragm in such a manner that one pole of each small magnet (thatof the shorter leg) shall press upon one of the outer poles of theinultipolar magnet, and the others, fastened in a cluster upon thecenter of the disk, shall vibrate as a whole before the main pole of themultipolar magnet. In the use of this plate I dispense with the smallinduction-coils, retaining the larger one upon the central pole. Theobject of this part of my invention is symmetrically distributed anumber of poles of the opposite character, all acting as one magnet,combined with a helix or helices and a vibratory plate, for the purposesset forth.

2. A compound vibrating plate for the telephone, consisting of a seriesof thin U-magnets, acting as one, attached to a non-magnetic ordiamagnetie diaphragm, essentially as set forth.

ASAHEL K. EATON.

itnesses DANIEL BREED, GEO. F. GRAHAM.

